The purpose of this study is to assess individuals suspected of having humoral immune deficiency. Such patients may not make antibody normally. Immunization with Bacteriophase 0X174 is a safe way of assessing the ability to make antibody in such patients. Because humans are not usually exposed to Bacteriophage 0X174, patients receiving intravenous immune globulin (IVIg), can be assessed for antibody production after receiving Bacteriophage )X174. Ordinarily, patients receiving IVIg cannot be assessed for antibody production because they have passively received antibodies in the IVIg. The results of the study can be extremely useful in determining 1.)whether a patient has a defect in humoral immunity (antibody production) and 2.) whether a patient receiving IVIg still needs to receive IVIg.